<!DOCTYPE html>
<html lang="zh-CN">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div {
            width: 200px;
            height: 200px;
            border: 1px solid blue;
            border-top: 1px solid red;
            margin: 100px auto;
            background-color: rgba(22, 30, 12, 0.2);
            padding: 20px;
            border-radius: 100px;
            float: left;
        }
    </style>
</head>

<body>
    <div class="left">这是左浮动</div>
    <div class="right">这是右浮动</div>
</body>

</html>